New Research on Bedsharing and Infant Breathing

by Alice Callahan on July 25, 2012

Berthe Morisot [Public domain], via Wikimedia Commons

A study published online last week [1] in the journal Pediatrics gives new information on the breathing environment for bedsharing and crib-sleeping infants. Dr. Sally Baddock and colleagues from the University of Otago in New Zealand conducted the study.

This study included 40 routinely bedsharing infants and 40 routinely crib-sleeping infants, all of which were healthy and between 0 and 6 months old. Few mothers in the study were smokers, and most of them breastfed.

The infants and mothers were videotaped on two consecutive nights. On the second night, the babies were also fitted with several sensors for physiological measurements. Their blood oxygen was measured by pulse oximetry. Other sensors measured breathing rate, and thermometers measured body temperature during the night. The air in the space directly around the infant was also sampled periodically through a small tube attached to the infant’s face. Although these measurements bring to mind a picture of lots of tubes and wires, the authors say, “All leads were secured to allow mothers to handle infants freely during the night.”

The purpose of the study was to better understand the breathing environment for bedsharing and crib-sleeping infants. Specifically, the study reported two main measures:

1. Desaturation events.Oxygen saturation is a measure of the percentage of arterial blood cells that are carrying oxygen. The higher the percentage, the more oxygen is circulating in the body for cells to use. Oxygen saturation of 95-100% is normal, and baseline measured in the infants in this study was 97.6%. A desaturation event was counted if oxygen saturation dipped below 90% for at least one second, indicating a period of low oxygen availability for the baby.

2. Rebreathing events. A rebreathing event was noted if the carbon dioxide in the air around a baby’s face increased above 3%. Carbon dioxide is normally 0.039%, so 3% is very high. This is called a rebreathing event because it indicates that the baby must be breathing air that had just been exhaled (and therefore higher in carbon dioxide and lower in oxygen), either by the baby or the mother. It usually occurs if the baby’s head becomes covered by something like a blanket. We know from previous infant studies that if the carbon dioxide level in the air gets above 3%, babies will increase their rate of breathing to try to return their body to normal carbon dioxide and oxygen balance [2].

The authors wondered if babies sleeping in beds next to their mothers or alone in cribs would be exposed differently to these minor respiration challenges.

Here’s what they found:

On average, babies that slept in cribs had 3.1 desaturation events per night, while bedsharing babies had 6.8. In the bedsharing babies, many these periods of low oxygen availability were associated with warmer body temperatures.

During the study, only one crib-sleeping infant had a rebreathing event. This occurred when a muslin swaddle ended up around the baby’s face for part of the night. Among the 40 bedsharing infants, 22 of them had a total of 79 rebreathing events. During the rebreathing events, the babies’ respiration rates and heart rates increased, but their oxygen saturation did not change. In other words, the babies seemed to be able to respond appropriately to the challenge of high carbon dioxide to maintain their blood oxygen at normal levels.

Why did the bedsharing infants have so many rebreathing events? Some of them happened because the infants were sleeping on their tummies, in the prone position. In one case, a mother was breathing directly into her infant’s face as they slept together. However, 70% of these rebreathing events happened because the infants’ heads were covered with blankets. The same authors reported in an earlier paper [3] that head covering usually occurred when an adult shifted body position during the night and that most of the time (but not always), mothers eventually ended up uncovering their babies’ heads.

OK, so bedsharing infants face more breathing challenges during the night. What does this mean? Is it a problem? Does it have any relevance to the risk of SIDS?

In this study, these low-risk, healthy infants seemed to respond appropriately to breathing challenges. When they were exposed to high carbon dioxide, they increased their respiration rate in order to get more oxygen and blow off carbon dioxide. When their faces were covered, their mothers often uncovered them, sometimes in response to the baby waking and crying. The truth is that we don’t know if these minor challenges pose a real risk to healthy infants.

But what happens if the baby is sick, premature, or has been exposed to cigarette smoke? These factors may affect a baby’s ability to respond appropriately to high carbon dioxide or low oxygen. What if the mother is less responsive due to drugs or alcohol? She may not wake when the baby signals distress. The authors also point out that repeated exposure to low oxygen, as happens during the desaturation events, has been shown to blunt arousal responses in animals. They state, “We suggest that frequent desaturations in vulnerable bedsharing infants could be a contributory factor in their risk for SIDS.”

The authors of this paper conclude with the following statement:

“The presence of the mother and other bed-partners, and the physical environment of the adult bed clearly led to a different sleep environment for the bedsharing infant compared with the crib-sleeping infant, resulting in beneficial and potentially compromising situations. Infant homeostatic responses and frequent maternal interactions seemed to keep these low-risk infants safe. However, we suggest that it is potentially hazardous for an infant to sleep in the same bed as their parent, if the infant and/or mother are unresponsive. We acknowledge that bedsharing is a practice valued by many; thus, it is important to identify the specific dangers related to this practice… Studies with high-risk infants are required to advance understanding of the specific mechanism(s) leading to their increased vulnerability.”

We know that SIDS occurs more often in babies that bedshare. We also know that the risk is clearly higher in babies that are very young (<3 months), babies exposed to smoking, those sleeping in beds with lots of loose bedding, and those sleeping with adults that are impaired by alcohol or drugs [4]. Routine bedsharing does not seem to increase the risk of SIDS [5].

Many parents choose to bedshare because they enjoy the closeness to their babies, because it makes breastfeeding easier, and sometimes because their babies refuse to sleep any other way. Bedsharing is also the norm in many cultures around the world. Increasing our understanding of the physiology of babies sleeping together and apart from their parents will only help us to understand and minimize the risks associated with SIDS.

If you bedshare, this study illustrates some important cautions:

Minimize bedding and pillows in your bed. When is someone going to make an adult-sized, zip-up sleep sack for the breastfeeding mother?

Take care to keep your baby from getting overly warm.

No smoking during pregnancy or while the baby is bedsharing (even smoking outside the bed increases the risk).

Avoid drugs and alcohol, which can impair your ability to respond to your baby during the night.

My understanding is that “bedsharing” when referring to SIDS research also includes sofas and chairs and recliners, which is where the majority of suffocation incidents occur. Are you referring to SIDS being most common in babies that bedshare, or suffocation – two distinct issues?

Hi Pam – The authors of this paper used the term SIDS, but you are right that many infant deaths during sleep are caused by suffocation, which is distinct from SIDS. However, in practice, distinguishing between SIDS and suffocation or other causes of sudden death in practice is difficult, and they share many of the same risk factors. They have not always been well-differentiated in the epidemiological research, which certainly muddies the data. Regardless, we obviously want to do our best to understand these risk factors and minimize the risk of infant deaths, whatever the ultimate cause. Sleeping on sofas and other plush surfaces is definitely a big risk factor for both SIDS and suffocation, but this study was specifically looking at babies sleeping in beds.

“We know that SIDS occurs more often in babies that bedshare.”
Can you please qualify this? As far as I know, studies that might lead to this conclusion have not distinguished between co-sleeping in a bed and co-sleeping on another surface such as a couch.
The study seems to be poorly designed. I would like to see one that compared SAFE bed sharing with SAFE crib sleeping. Of course if you compare SAFE crib-sleeping to bed sharing of various safety levels, the study would be biased towards crib sleeping.
SAFE bed sharing means:
no alcohol, drugs or tobacco for either parent.
no bed sharing with sibligs or pets or anybody else than mum (and dad)
no loose clothing on parents of children
long hair tied back
no blankets or doonas that could cover the baby (it IS possible, even without a sleeping bag for mum)

Also, your conclusion that at-risk babies could be affected differently by those breathing changes goes both ways. As you pointed out yourself, in bed-sharing infants mothers (and babies) responded appropriately. Consider that in sole sleeping at-risk babies the mother will very likely not be aware of a change in baby’s breathing so will not be able to help (rouse baby etc.)

Hi Alex,
The data on bedsharing and SIDS are really complex, and I want to look at them more closely for a separate post. As you point out, there are many identified risk factors, and recent research shows that most cases of SIDS have multiple risk factors involved – not just cosleeping alone. Sleeping on a couch or other plush surface definitely increases the risk, but sleeping in a bed does not necessarily eliminate the risk. For example, see the study by Tappin et al: http://www.ncbi.nlm.nih.gov/pubmed?term=16027691

I did qualify my statement by stating what seem to be the biggest risk factors for SIDS and by noting that routine bedsharing does not seem to increase the risk of SIDS – that has been found in a couple of studies. I know many families bedshare carefully and conscientiously, and I actually believe that it can be done safely, but I can’t say that I know that for sure because I haven’t seen solid data on it. I’m afraid those data don’t exist and that obtaining them will be very difficult. To be honest, I think the best judge of whether a bedsharing situation is safe is probably the mother sleeping next to the baby – provided that she is informed and educated about safe sleeping. It will always be tough to model these very complex, multifactorial risks using epidemiological methods.

As to the study population in this study – this is a great point. Here’s what we do know about this group: “Bed-sharing infants were recruited through local postnatal groups and media advertising.” 100% of bedsharing infants were breastfed (88% of crib-sleeping infants). “Maternal smoking was more common in the cot group (25%) compared with the bed-sharing group (8%).” And “The practice of bed sharing was reported to be adopted by mothers because of factors such as the ease of breastfeeding, the provision of a close and secure environment for the infant, a more settled infant, and a natural environment.” While these mothers may have not practiced perfect safe bedsharing, I think it is probably a pretty good representation of reality among intentional bedsharing families.

Your final point is well-taken, and it is definitely a viable hypothesis – we just don’t have data on it. I think that if I was mother to an at-risk baby, I would be most comfortable having her in a sidecar cosleeper attached to the bed so that I could monitor her closely without fear of some of the risks that may come with sleeping on the same surface.

Thanks for your critical reading of my posts. Again, I hope to research this topic in more depth soon.

They make sleep sacks for adults – they’re just called wearable blankets, and some brand names are Snuggie, Slanket, Snazzy Napper, and Forever Lazy. My dad would wear one around the house in the winter rather than turning up the heat in the house.

I know you summarized, but did all the parents bedshare according to the safety recommendations? You mentioned only that most babies were breastfeed, and I know that the safety recommendation is that you are NOT supposed to bedshare if you’re not breastfeeding.

Also, as I’ve seen in recent news stories the trend is towards blaming SIDS deaths on bedsharing, when the cause of death is, in fact, indeterminate. This prejudice should be allowed for when reporting such results in studies (esp retrospective ones), and I don’t know that it is.

b – I thought about the Snuggies, but they actually seem to be really loose to me and probably wouldn’t be safe for bedsharing. I said this in part as a joke, but I do actually really like the design of infant sleep sacks:) The safest option is probably to either wear warm clothing or for each adult in the bed to use their own light blanket so that baby doesn’t need to be covered by it.

See my above comment to Alex for a more detailed description of the families in this study.

Honestly, I think a few decades down the road, we will have successfully figured out what an “at risk” baby looks like, and having done so, we’ll be able to stop worrying about whether bedsharing increases risk, etc. These babies probably have a biologically diminished arousal capacity, and once we figure out how to identify them, we should be able to target the “safe sleep” behaviors to babies who are really at high risk.

That is, I think the study shows something very interesting – low-risk babies (I’m assuming most of these are) are able to cope with changes in their sleep environments appropriately. It’s the higher-risk babies, as you say, who probably can’t. I’m more interested in this study for what it says about the ability to regain homeostasis in a low-risk baby than about hypothetical SIDS risk factors.

I do have an emotional dog in this race, or did – Zachary absolutely could NOT sleep on his back, and so I flipped him to belly at six weeks old, and he went from “pseudo colicky” to “great sleeper, shiniest baby ever” literally overnight. So I’d love to see the generalized “back to sleep” recs go away. I feel like we’re torturing babies (sleep deprivation) in order to save them, and most of them don’t need saving.

Rachael, I just couldn’t help but reply to your comment. The part about placing baby on their bellies to sleep. My kids just would not sleep on their backs. I rocked them to sleep in my arms for ages, I wore them in slings etc. They were both fantastic sleepers. My daughter would sleep 5 and 6 hour stretches in the first week – only while in the sling or my arms. The second I placed her on her back, she woke up and screamed. My personal completely unscientific observations were these: Our babies are in the foetal position while in utero. That means curved backs and knees pulled up. They have a curved back while worn in a sling or while cradled in our arms, too. If you place them on their backs on a firm mattress you straighten their spines which does not seem to be a natural pose.
I am aware that placing babies on their backs is advised to reduce the risk of SIDS and I am not advising against it. But my own experience was that my babies slept well on their sides and bellies and really poorly on their backs. This is actually the reason I started co-sleeping. I had my babies sleeping on their tummies while lying on my chest. I felt very safe that way but I am aware that it goes against safe co-sleeping recommendations. Once they got too heavy for that, I had them sleeping on their sides with their heads resting in the crook of my arm to stop them from rolling onto their bellies.

I was under the impression that it was exactly BECAUSE babies sleep longer and deeper that stomach sleeping is not recommended. It is estimated that the original recommendations to place infants on their stomach caused the deaths of over 50,000 babies.

I personally place my babies on their sides, but I’m a co-sleeper so already breaking the rules anyway 😉

Of course that’s the reason – but it’s not really fair to say that stomach-sleeping causes SIDS. It’s that back-sleeping reduces risk. And probably only for the subset of babies who were at risk in the first place – most babies probably aren’t at any serious risk of SIDS, regardless of sleeping position.

That’s kind of my point – we deliberately make our babies have bad sleep in order to protect them from SIDS, and, for one of mine, it was actual torture to be forced to try and sleep on his back. He simply couldn’t learn to do it. It would be nice to figure out who really IS at risk, and how to screen for it, so we can stop worrying over every baby, and start worrying about the at-risk babies.

I want my babies to be allowed to sleep more deeply. Not to mention the risk he was at riding in cars with parents who weren’t getting more than 90 minutes’ sleep at a time.

If I recall correctly, it’s also that babies on their stomachs are more likely to have rebreathing events as well as the increased suffocation chances. They don’t have the muscle control to turn their heads sufficiently to improve their airflow.

Rachael, I totally agree that the finding that most babies, at least those in this study (should have been low-risk based on what we know about them) were able to compensate for changes in oxygen availability and regain homeostasis is the most interesting thing this study tells us. Actually, it is the only thing it tells us, and everything else is speculation! I’m fascinated by the idea that we may one day be able to test babies to determine which are high-risk for SIDS. I hope you’re right that that isn’t too far off. It certainly would decrease a lot of the angst we have about our babies’ sleep.

As to the back-to-sleep recommendation, it has clearly decreased the number of babies dying of SIDS, and it needs to be the prevailing public health message now. But I agree that prone sleeping is probably not a problem for most babies, and it sure would be nice to know which ones are at risk so that babies like Zachary and moms like you can get the sleep you need.

The last time I looked into this (when I was pregnant with Zachary), I found some really interesting material on dopamine levels in SIDS babies, and I can formulate a hypothesis about how low dopamine could be causative…also, there is a genetic component (as with everything), and that implies changes in gene expression that can increase (or, presumably, decrease) risk.

The research is really tough to do the “right” way, given the huge ethical issues, but I think we know enough right now to start asking the “what’s different in babies who die of SIDS compared with those who don’t” question at a molecular level, rather than just assessing risk factors like sleep position and prematurity.

I love the idea of a sleep-sack for the breastfeeding mom! Both of my babies were born in July, which meant that in order to sleep at all, we needed the air conditioner on, which meant that I was cold at night even with a warm bundle near me. We mostly used a cosleeper, rather than actually having the baby in bed, but I do remember several weeks when my first son wouldn’t sleep any other way except on my chest, and it was tough to stay warm without worrying about his little head getting covered.

Thank you for presenting this research without saying that cosleeping is automatically bad. I was happy with my choice to use a cosleeper, but I also did love sleeping with the munchkins and I can see why it is such a valued practice. This kind of research can help make sure it’s done as safely as possible, and give people facts as to why the recommendations are important.

I’m one of those people who can’t sleep without something covering my body to my chin. I need a sheet even in the hottest weather. In my limited experience with cosleeping, I was constantly worried about covering BabyC’s head without being aware of it. I think I might be able to make do with a sleep sack sort of thing though.

Anyway, I don’t think that cosleeping is automatically bad – not at all. It does seem to add more variables to consider, though, and it puts more responsibility on the parents to make sure they’re doing it safely. That’s why research like this is helpful – so that we can better understand how babies cope with their environment while sleeping.

We used a moses basket with the first baby and a cosleeper (the next to the bed kind) with the second, so that I could have the baby nearby (often with my hand on her, to help her sleep) without having her in my bed. That was our compromise. We didn’t start true bedsharing until the baby was older- at about 18 months with the first and at about 9 months with the second. That got everyone more sleep.

The nice thing about the moses basket was that we could take our baby’s sleep environment with us if we traveled (by car), and my husband could start the night with her in the living room- she was safe in her basket, and he slept on the sofa- until her second wake up (he bottle bed her for her first wakeup), when he’d bring her in and turn her over to me to nurse her. That bought me a couple of hours more of sleep, which was a huge help, since she was (and is) a low sleep needs kid.

The nice thing about the cosleeper was that I didn’t have to bend over to reach the baby! And with an older sibling in the house, the staggered night shift thing never really worked the second time around. Luckily, she was a slightly sleepier baby!

You want to hear a funny story? We had a cosleeper for BabyC, too. She slept in it for the first 3 months of her life. However, I put it at the foot of our bed. I had this idea that my husband would be more involved with caring for her at night if she was equidistant between us. The reality was that he worked lots of nights, traveled lots, and slept way too soundly when he was at home. I woke many mornings in the yogic child’s pose at the foot of the bed, where I’d moved at some point in the night to pat BabyC and help her return to sleep. God, why didn’t I move that cosleeper next to me?! Not sure what I was thinking there… Next time, I’ll do things differently.

I find the single incident of rebreathing in the crib sleeping infant a bit unnerving. My daughter falls asleep by pulling her sleep sack up over her face. When she hits a light sleep transition she does the same thing. I got a muslin sleep sack because the cotton one I had didn’t seem quite breathable enough and I didn’t want to be awake all night pulling her sleep sack down and potentially waking her up. It’s nice to know that low-risk infants can handle some of these incidences and I do know that I could easily breathe through a muslin sleep sack (I checked). Wish my daughter had another self-soothing technique, but at this point I’m not sure quite what I’m going to do other than move the sleep sack when I can while I’m awake.

They actually included a picture from the infrared camera of the crib-sleeping infant with the muslin wrap pulled over the head. It looks like it is several layers of fabric, swaddled, arms included in the swaddle. They report that the baby pushed the fabric up over the face several times during the night, and the photo shows that the baby’s head is barely visible peeking out from the top of the swaddle. I would think that a one-layer muslin sleep sack would be fairly breathable and fitted enough that your daughter can’t pull it completely over her head? Otherwise, maybe you could try a smaller sleep sack to limit the amount of fabric she can pull?

BabyC used to always suck on the upper hem of her sleep sack as a self-soothing technique when she was an infant – it turned a nice rusty yellow color:) Yet she was never interested in a pacifier.

She does cover her entire face with it up to her forehead, but only rarely. Usually she just gets a bump of it up in front of her face and it’s actually not covering her face at all. Every time I’ve turned on the video monitor in the middle of the night and found the sleep sack on her face I jump up and move it, and she’s always fine. It is just a single layer and I pushed my nose right up to it and I at least breathe as easy as if there was nothing there. Maybe as it shrinks and she grows there will be less and less fabric for her to pull on, although she’s a master and getting any and all fabric near her over her face even when awake! Thanks for the ideas.

With my first daughter we were too scared to deviate from popular recommendations. She NEVER slept in the bed with us but once and I couldn’t sleep a wink! She slept in a cosleeper next to me but slightly on her left side which seemed to help with the reflux symptoms. With my second daughter she had much more severe reflux, and was born prematurely. She was so restless and such a poor sleeper when she slept on her back. One day I had her, while she was awake, on her stomach as she’d had super strong upper body strength from the get go. Before long she fell into the most peaceful sleep I had see her experience since birth so that night did I not only sleep with her in the same bed but I had her on her stomach! I had one quilt on top of us and the mattress had a fitted sheet. She’s been able to lift and turn her head without problems. It’s only now that she’s just over two months and starting with the army crawl that I’ve moved her to the co-sleeper next to my bed but she’s still on her stomach. I think you just intuitively know what’s best for your child and the fact that they continue to have studies like these only means that no one has figured out a right or wrong way. Maybe science isn’t suppose to figure it out for us maybe it’s just a mom thing.

Hi Sherry – While I think that each of us needs to weigh the risks and benefits of decisions for ourselves and use our intuition and knowledge of our babies, I do think that science is incredibly valuable in helping to untangle the risks associated with babies dying during their sleep. The recommendation that babies be put to sleep on their backs has clearly reduced the incidence of SIDS, and we would not know that without research. I do believe that until we have a better way to assess individual risk of SIDS, that the safest sleep position for a baby is on her back.

I agree with you completely about the science and am grateful for the guidelines they’ve provided the public but I am also glad I had the courage to follow my intuition knowing it was my choice for my baby. My hope is that there continues to be a passion for a resolution to the sleep position issue (and the funding!) so that all babies/families can sleep happily ever after 🙂

Thank you for presenting this information. I have always wondered about cosleeping. My daughter and second son both slept in a seperate crib and this did give me peace of mind that I would not accidentally cause harm to them in my sleep. Having lost my first son I am overly cautious (he died shortly after birth, not SIDS relates). The idea of being close to my children while we sleep is appealing to me but I get in lots of cuddles during the day.http://www.WantedChosenPlanned.com

Alexis, one of the primary reasons why I chose not to cosleep was that I had too much anxiety about causing harm to my baby in my bed. I coslept with BabyC for a couple of weeks when she was very young and I was very sleep-deprived. She would start the night in the cosleeper but then stay in bed with me after her first waking/nursing. Every time I woke during the night and in the morning, my heart would be pounding and I would have a few seconds of frantic agony until I saw that she was safe. Maybe I would have come to terms with this if I had made a real commitment to cosleeping and it felt more comfortable to me, but it wasn’t a good fit for me. I felt like she was safer in her own sleeping space.

This is one of James McKenna’s safe sleep guidelines, and I took it to heart: “It may be important to consider or reflect on whether you would think that you suffocated your baby if, under the most unlikely scenario, your baby died from SIDS while in your bed. Just as babies can die from SIDS in a risk free solitary sleep environment, it remains possible for a baby to die in a risk-free cosleeping/bed sharing environment. Just make sure, as much as this is possible, that you would not assume that , if the baby died, that either you or your spouse would think that bed-sharing contributed to the death, or that one of your really suffocated (by accident) the infant. It is worth thinking about.”

Of course, if my baby died while sleeping in a crib, I might wonder if things would be different if she was sleeping next to me, but I had to go with what I felt most comfortable. Others have to do the same and might make a different choice.

Thanks for your comment and sharing your experience. Congratulations on the birth of your new baby. I checked out your blog – looks like a wonderful record of the process of grief and birth.

I really enjoyed this article. we chose not to bedshare. one of the main reasons i think we made the right decision is we are one of the only couples we know who sleep all night and have a child who sleeps in his own room w/ out waking up for anything.

i do not know how related these things are, but when he was 6 months, we moved him into his own room. i think this gave him some independence. i don’t think he was aware, but i know our friends who did or do bed sharing have trouble even getting their kids to nap, but our son now at 1 1/2 walks right to his room and crib when he is tired.

i never felt comfortable with the safety aspect of co-sleeping and this post made me feel much better about that.

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Welcome! I'm the author of The Science of Mom: A Research-Based Guide to Your Baby's First Year, published by Johns Hopkins University Press in 2015. I write about science, health, parenting, and nutrition here and for other print and online outlets.
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